The present disclosure relates to a monolithic spectrometer, an optical instrument, and a method for spectrally resolving light.
A spectrometer is an instrument used to investigate a property of light as a function of its portion of the electromagnetic spectrum, e.g. for spectrally resolving the light. The term ‘light’ as used herein includes all forms of electromagnetic radiation such as visible, infrared and/or ultraviolet radiation. Typically, a spectrometer comprises reflective and/or refractive optics for guiding and shaping the light as well as a spectral resolving element such as a grating or prism for diffracting and/or dispersing the light in a wavelength dependent angle. Depending on the angle, different spectral components of the light can be imaged at different locations along a spectral axis in an imaging plane of the spectrometer. A sensor can be arranged for detecting spectral components of the light in the imaging plane.
A monolithic spectrometer comprises a body of solid material shaped to guide the light along an optical path inside the body. The material of the body is transparent at least to the wavelengths of light for which the spectrometer is intended to be used. For example, depending on the intended use, the material can be transparent to visible and/or infrared and/or ultraviolet radiation. The body shape comprises optical surfaces to transmit, reflect, shape (e.g. collimate or focus), refract (e.g. bend or disperse), and/or diffract the light as it travels along the optical path. Optionally, the optical surfaces may be coated, e.g. with a reflective material, or an optical piece such as a mirror or grating can be adhered to the optical surface to provide or aid the optical function of the surface. Advantages of a monolithic spectrometer over a regular spectrometer may include compactness, stability, and/or manufacturability.
For example, U.S. Pat. No. 8,345,226 describes various embodiments of monolithic spectrometers including Czerny-Turner, crossed Czerny-Turner, and Fastie-Ebert configurations. For example, European patent application 2,857,810 A1 describes a monolithic spectrometer of a particularly compact design.
It is desired to improve the known monolithic spectrometer to cover a broad wavelength range while maintaining adequate spectral resolution.